Method of treating soap



Patented Jan. 15, 1946 METHOD OF TREATING SOAP John W. Bodman, Winchester, Mass., assignor to Lever Brothers Company, a corporation of Maine No Drawing. Application February 6, 1943, Serial No. 475,005

be deleteriously affected to a material degree by Claims.

The present invention relates to a method for improving the appearance of soap products and more particularly, to a method which may be used to form a polished or glossy surface on soap.

Soap products made in accordance with conventional soap makin processes are characterized, for example, after molding, cutting, stamping or like finishing operations, by a relatively dull or lusterless surface. The appearance of soap products, particularly cakes and bars, is an important characteristic, and the art long has sought a practical method for forming a soap product which has a shiny or glossy surface as compared with the dull or lusterless appearance characteristic of conventional soap products.

It has been attempted heretofore to improve the appearance of the surfaces of soap products, for example, by means of mechanical treatments such as burnishing operations. However, such methods have not been successful commercially, possibly because the resultant improvement in the ap earance of the soap products, if any, is not sufficient to justify the d'ifiiculties and added costs involved in such operations. Accordingly, despite the demand for soap products having an improved appearance, it is the general com mercial practice to market soap as itcomes from conventional finishingoperations, i. e., having a dull or lusterless appearance.

In accordance with the present invention, however, it is possible to enhance the appearance of soap products by a method which may be carried out in a convenient manner and which does not materially add to the cost of manufacture. As a resultof the present invention, therefore, it is possible to provide conventional soap products with a. glossy or bright surface by a method which is practical commercially.

The method of th present invention is believed to be a departure from the prior art, for example, because it does not rely upon a mechanical treatment of -the soap surfaces but instead, may comprise a physio-chemical or thermal modification, or both, of the soap surfaces. In this respect, it is distinct from the burnishing operations proposed heretofore but which have been unsuccessful commercially.

It is an advantage of the method of the present invention that it may be applied to any soap products prepared. in any known manner. If desired, it may be applied to products which heretofore were considered by the art to be finished products ready for marketing. On the other hand, the improved surfaces imparted to the soap in accordance with the present invention may not some finishing operations such as stamping, and accordingly, it is intended that the method of the present invention shall be applicable to the treatment of soap at any time after solidification. In general, however, it will be preferred to apply the method of the present invention to soap after it has been formed into the desired shapes for marketing, such as bars, cakes and tablets. As a specific example, the method of the present invention may be applied to the soap before or after stamping, whichever is the more convenient, and prior to wrapping or other pack-.

aging if these operations are used. The stamping operation and the wrapping or packaging, it has been found, does not noticeably diminish the gloss of soap products resulting from treatment in accordance with the invention. In general, it may be preferred to apply the method as the last stage before wrapping to avoid any possible marring of the polished surfaces by subsequent operations, but as stated above, this is not essential.

The saponification and other manufacturing operations in the preparation of the soap products to be treated in accordance with the present invention do not form a part Of the invention. In view of the present disclosure, it will be apparent that the method of the present invention is applicable'to the treatment of soap products prepared in any known manner. It is not even necessary that the method be practiced as a part of a soap making operation, for any conventional soap products, may be treated even after standing for prolonged periods of time.

The method of the present invention may be carried out, for example, by subjecting the surfaces of soap for a brief period of time to the action of an aqueous liquid to be described more particularly hereinafter. This may be accomplished conveniently, for example, by dipping the soap into an aqueous bath which may be heated, if desired, whereby after drying, the soap is found to have a polished or glossy surface.

The actual mechanics of treating the soap with the aqueous liquid is not believed to be critical and this may be done manually or, if desired, any suitable apparatus to facilitate the treatment may be employed. For example, the soap may be moved continuously or intermittently by means of a conveyor belt through a bath or impinging streams of the aqueous liquid, or may be suspended therein by means of wires or other supports. All such useful expedients are deemed to be within the skill of one versed in the art and are not claimed herein as part of the invention.

The aqueous liquid in its most elementary form may comprise hot water without the addition of other ingredients, and this in many instances may prove to be the most economical form. However, it may be desired, depending upon the operating conditions and the results it is desired to attain, to modify the treating liquid by the addition thereto of one or more water miscible organic liquids as discussed more fully hereinafter.

The ingredients of the treating liquid, in addition to water, may comprise water miscible or- 1 ganic solvents of soap such as, for example, the

water miscible lower alkyl alcohols or acetone. By lower alkyl alcohols is meant the alkyl alcohols having less than six carbon atoms per molecule. As specific illustrations of the use of such alcohols, a desirable satin-like gloss was ob tained when the treating liquid included, for example, water and ethyl alcohol, or water and isopropyl alcohol.

The relative proportions of the ingredients of the treating liquid may be varied over a wide range depending upon the conditions of treatment and results desired. In the specific illustrations set forth above, for example, the water and alcohol were present in substantially equal proportions, i. e., 50% water and 50% ethyl or iso-propyl alcohol. In general, the proportion of the organic solvent of soap to water should not exceed the maximum solubility of the solvent in the water. It is preferred to have the treating liquid entirely homogeneous to insure uniform results and avoid any spotty effects. With solvents which are miscible with water in all proportions, a range of about 25 to 75% may be preferred. Proportions other than those specifically set forth by way of example may be used. In general, any concentration may be found to be satisfactory which does not excessively dissolve the soap under the conditions of operation.

While it is not intended that the invention shall be limited to any theory of operation, it has been observed that the solvent power of the treating liquid does not appear to be a controlling factor as shown, for example, by the fact that a mixture of ethyl alcohol and benzene, which is an excellent solvent of soap, produces no gloss when utilized alone as a treating liquid in accordance with the invention. On the other hand, water or a mixture containing water and a water miscible solvent for soap, is effective for improving the appearance of the soap. It may be, therefore, that a plausible assumption is that the improvement of the appearance of the soap involves hydration of the soap surfaces and that the presence of a water miscible organic solvent for the soap facilitates the hydration. The foregoing explanation is given merely to assist one skilled in the art to understand and utilize the invention, and it is not intended that the invention shall depend upon any such explanation or theory of operation.

The temperature at which the treating liquid is maintained during the treatment of the soap is susceptible to wide variation in accordance with the invention. In general, the preferred temperature may be found to exist throughout a wide range depending upon the composition of the liquid, the method of treatment, and the characteristics of the soap treated. When water alone is used, it is preferred to heat it to at least a temperature at which it is hot to the touch, for example, at least above 100 F. -Desired results have been obtained, fofexamplr, by maintaining the water at a temperature of about 175 F. or in the range of 150-200 F. When an organic liquid is added to the water, the same treating temperatures may be employed. In general, however, lower temperatures may be effective when utilizing water admixed with an organic liquid to obtain the same degree of polish as when water is utilized alone. For example, with the proper choice of liquid, temperatures as low as room temperature may be utilized effectively. This phenomenon may be availed of to minimize the heating costs or make heating unnecessary, and also if the added liquid is volatile, to decrease the evaporation loss. In general, a lower temperature may be utilized if the time of treatment is prolonged or conversely, if it is desired to shorten the time element, higher temperatures may be employed. Referring to the specific examples given above by way of illustration, a 50-50 mixture of water and iso-propyl alcohol, for example, may be utilized to impart a satin-like gloss to soap when at a temperature of about F. or in the'range of 70 to F. When utilizing a 50-50 mixture of ethyl alcohol and water, a somewhat higher temperature of the order of about 125 F. or in the range of 10o-150 F. imparted a satin-like gloss to the soap treated. The foregoing temperatures are set forth to illustrate the practice of the in vention and to facilitate the use thereof, but it is not intended that the invention shall be limited to the selection of a specific temperature or temperature range inasmuch as in view of the present disclosure, this may be regarded as within the skill of one versed in the art. In general, it will be observed that the temperature of the liquid is too low when the polishing action is not sufl'iciently marked while at too high a temperature, the solvent action of the liquid may be so increased as to cause undesirable dissolution of the soap surfaces.

The length of time during which the surfaces of the soap may be treated with the heated treating liquid to improve the surface appearance of the soap is not critical and may be varied over a wide range, if desired. It will be apparent that inasmuch as the composition and temperature of the bath may be varied over a wide range, these factors also may influence the amount of time required for treatment. In general, when a liquid containing a higher concentration of soap solvent is used, or when the treating liquid is maintained at a higher temperature, a shorter treating period is generally required to obtain the same degree of polish. 'Io expedite the carrying out of the process, which is generally desirable in commercial practice, it may be preferred to maintain the operating conditions such that an improved appearance may be imparted to the soap by onlya relatively brief treatment with the liquid. For convenience, for example, it may be preferred to subject the soap to treatment for only a minute or less, as for example, by dipping although, if desired, longer treating periods may be employed. In general, it is preferred to limit the length of treatment to the extent necessary to avoid excessive dissolution of the soap in they treating liquid. When the treatment is carried out after the soap has been stamped, it may be preferred to use a shorter time interval to avoid blurring of the design or lettering if this is found to occur.

After treatment of the soap surfaces with the treating liquid, it is necessary to dry the soap.

In general, it is preferred to carry out the drying without permitting the soap surfaces to come into contact with anything else insofar as possibe, so as to avoid any possible marring of the soap surfaces. The soap surfaces may be dried simply by permitting the soap to stand or, if desired, the drying may be accelerated by placing the soap in a dry or slightly warm atmosphere. If more rapid drying is desired, it may be found to be more convenient to utilize conventional drying equipment. All such expedients are deemed to be within the skill of one versed in the art and are not claimed as part of the present invention.

Following the treatment of the soap in accordance with the invention, the soap may then be subjected to subsequent finishing operations, or if no other finishing operations are contemplated, the soap may be packaged if desired. In general, conventional packaging operations, including the use of automatic packaging equipment, does not materially affect the polish or glossy appearance which has been imparted to the soap surfaces in accordance with the invention.

In accordance with the invention, as described above, it is possible in a convenient and economical manner to provide a soap product with a bright or satin-like glossy surface greatly enhancing its appearance and consumer appeal. Moreover, the improved appearance has been found to be sufficiently permanent so as to be of value even after prolonged periods of storage.

It will be understood that the invention may be susceptible to many variations by one skilled in the art, and all such variations are intended to be included within the scope of the invention.

I claim:

1. A method of treating a piece of soap in solid form following the final shaping operations and prior to packaging and shipment to the user thereof, for the purpose of improving the appearance of the surfaces of the soap which comprises immersing the piece of soap for a brief period of time into a bath of water at a temperature of not less than 150 F. to permit the water to act merely upon the soap surface, and then drying the soap without otherwise disturbing the surface thereof.

2. A method of improving the appearance of solidified soap comprising immersing the soap for a brief period of time into an aqueous bath comprising water and a water miscible normally liquid organic solvent for soap, said bath being heated to a. temperature imparting a polish to the soap.

3. A method of treating a piece of soap in solid form following the final shaping operations and prior to packaging and shipment to the user thereof, for the purpose of improving the appearance of the surfaces of the soap which comprises hydrating the surfaces of the soap by bringing the surfaces of the soap into contact with an aqueous liquid comprising water and a water miscible lower alkyl alcohol.

4. A method of improving the appearance of solidified soap comprising immersing the soap for a brief period of time into an aqueous bath comprising 25 to 75 parts water and 25 to '75 parts of a lower alkyl alcohol which is miscible with water in all proportions, said bath being heated to a temperature of at least 70 F.

5. A method of treating a piece of soap following solidification and prior to packaging and shipment to the user thereof, for the purpose of improving the appearance of the surfaces of i the soap which comprises immersing the soap for a brief period of time into hot water maintained at a temperature of the order of 150 to 200 F., and then drying the soap without otherwise disturbing the surface thereof.

6. A method of improving the appearance of solidified soap comprising immersing the soap for a brief period of time into an aqueous bath comprising 25 to parts water and 25 to 75 parts ethyl alcohol, said bath being heated to a temperature of the order of to F.

7. A method of improving the appearance of solidified soap comprising immersing the soap for a brief period of time into an aqueous bath comprising 25 to 75 parts water and 25 to 75 parts iso-propyl alcohol, said bath being heated to a temperature of the order of '75 to 125 F.

8. A method of treating a piece of soap following solidification and prior to packaging and shipment to the user thereof, for the purpose of improving the appearance of the surfaces of the soap which comprises immersing the soap for a brief period of time into hot water maintained at a temperature of the order of about F., and then drying the soap without otherwise disturbing the surface thereof.

9. A method of improving the appearance of solidified soap comprising immersing the soap for a briefperiod of time into a bath comprising about 50% water and 50% ethyl alcohol, said bath being heated to a temperature of the order of about 125 F.

10. A method of improving the appearance of solidified soap comprising immersing the soap for a brief period of time into a bath comprising about 50% water and 50% iso-propyl alcohol, said bath being heated to a temperature of the order of about 85 F.

JOHN W. BODMAN. 

